package com.hmdp.utils;

import cn.hutool.core.lang.UUID;
import org.springframework.core.io.ClassPathResource;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.data.redis.core.script.DefaultRedisScript;

import java.util.Collections;
import java.util.concurrent.TimeUnit;

public class SimpleRedisLock implements ILock{
    private StringRedisTemplate stringRedisTemplate;
    private String name;


    private static final String KEY_PREFIX="lock:";

    public SimpleRedisLock(StringRedisTemplate stringRedisTemplate, String name) {
        this.stringRedisTemplate = stringRedisTemplate;
        this.name = name;
    }

    private static final String ID_PREFIX = UUID.randomUUID().toString(true) + "-";

    @Override
    public boolean tryLock(long timeoutSec) {
        //获取线程标示
        String threadId = ID_PREFIX + Thread.currentThread().getId();
        //获取锁
        Boolean success = stringRedisTemplate.opsForValue().setIfAbsent(KEY_PREFIX + name, threadId + "", timeoutSec, TimeUnit.SECONDS);
        return Boolean.TRUE.equals(success);
    }
    //提前读取脚本
    private static final DefaultRedisScript<Long> UNLOCK_SCRIPT;
    static {
        UNLOCK_SCRIPT = new DefaultRedisScript<>();
        //指定脚本位置
        UNLOCK_SCRIPT.setLocation(new ClassPathResource("unlock.lua"));
        //指定返回类型
        UNLOCK_SCRIPT.setResultType(Long.class);
    }

    @Override
    //解决分布式锁原子性问题
    public void unlock() {
        //调用lua脚本
        stringRedisTemplate.execute(
                UNLOCK_SCRIPT,  //预加载lua脚本
                Collections.singletonList(KEY_PREFIX + name),  //KEYS[1]
                ID_PREFIX + Thread.currentThread().getId()  //ARGV[1]
        );
    }

}
